Asymmetric TDD in flexible use spectrum

ABSTRACT

A method according to an embodiment of the invention includes receiving and transmitting signals over a time division duplex (TDD) communication path. Signals are received over the TDD communication path via a first portion of a first frequency band. The first frequency band is adjacent to a second frequency band and to a third frequency band. The first frequency band is different from the second frequency band and from the third frequency band. A first frequency division duplex (FDD) communication path can be operable in the second frequency band. A second FDD communication path can be operable in the third frequency band. Signals are transmitted over the TDD communication path via a second portion of the first frequency band that is different from the first portion of the first frequency band.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.14/028,179, filed Sep. 16, 2013, and entitled “Asymmetric TDD inFlexible Use Spectrum”, which is a continuation of U.S. application Ser.No. 13/105,279, filed May 11, 2011, and entitled “Asymmetric TDD inFlexible Use Spectrum”, now U.S. Pat. No. 8,537,732, which is adivisional of U.S. patent application Ser. No. 12/270,946, filed Nov.14, 2008, and entitled “Asymmetric TDD in Flexible Use Spectrum”, nowU.S. Pat. No. 7,969,923, all of which are incorporated in theirentireties by reference as though fully disclosed herein.

BACKGROUND

The invention relates generally to wireless communication systems andmore particularly to a communication method that uses time divisionduplexing.

In addition to traditional voice services, next generation wirelesscommunication systems have to support various different types ofmultimedia services, including broadcasts, video conferencing, andinteractive applications, for example. Many of these multimedia servicesmay require flexibility in their use of spectrum capacity to operateeffectively. The typical spectrum management approach is to assignfrequencies to a particular use. This approach, however, has becomesomewhat limited in view of the complexity and overlap between theoperations of next generation services and applications. One regulatorysolution has been the introduction of flexible-use spectrum in whichusers of assigned portions of spectrum have more freedom to decide whichtechnologies and services to deploy. In this regard, flexible-usespectrum can allow spectrum users to make timely commercial choices andcan let market forces determine which competing technologies andservices will be offered in a particular frequency band. Such approachcan result in a more effective use of spectrum than that which occurs byimposing a technology or a service by regulation. As a result of theseefforts to open up the spectrum, new user-based communication techniquesare being considered that address aspects that are particular to nextgeneration services and applications. For example, communication methodsthat include duplexing techniques or schemes that incorporate theinherent asymmetry in data flow that is characteristic of manymultimedia services are being considered for next generation wirelesscommunication systems.

Duplexing techniques include time division duplexing (TDD), frequencydivision duplexing (FDD), and/or hybrid duplexing, the latter of whichincludes aspects of both TDD and FDD schemes. In TDD, bidirectionalcommunication or data flow is implemented through a communication linkby separating the communication time within a given frequency bandassociated with the communication link into alternating transmissiontime slots and reception time slots. A time guard is used between timeslots to reduce or minimize the likelihood of interference. In thisscheme, a satellite or a base station, for example, can allocate anumber of transmission time slots different from a number of receptiontime slots to a mobile device within a given time interval to produceasymmetric data communication. As the area of coverage provided by thesatellite or the base station increases significantly, the guard timebetween time slots may be increased to compensate for delays that resultfrom a longer signal round-trip between the satellite or base stationand the mobile device. The increased delay can reduce the communicationefficiency of the TDD scheme. In many instances, however, the time guardis sufficiently small even when large areas of coverage are concernedsuch that the TDD scheme efficiency remains adequate for many servicesor applications.

In FDD, bidirectional communication or data flow is implemented througha communication link by partitioning a given frequency band associatedwith the communication link into separate transmission and receptionfrequency bands that operate concurrently. Because the transmission andreception bands are separate from each other to reduce the likelihood ofinterference, no time delays occur associated with the transmission orreception of signals (i.e., no round-trip delays). Although the FDDscheme may be suitable for large areas of coverage because time delaysdo not play a significant role, the fixed and balanced nature of thetransmission and reception frequency bands limit the flexibility that isnecessary for asymmetric data communication in next generation wirelesscommunication services. Some FDD schemes achieve asymmetry by using anauxiliary frequency band separate from the paired transmission andreception frequency bands to provide additional capacity in onedirection of the data flow. This approach, however, requires thecommunication system to include additional hardware and/or software tohandle the separate frequency band through which asymmetry is achieved.

Thus, a need exists for new methods for asymmetric communication inwireless communication systems.

SUMMARY

One or more embodiments of a method include receiving and transmittingsignals over a time division duplex (TDD) communication path. Signalsare received over the TDD communication path via a first portion of afirst frequency band. The first frequency band is adjacent to a secondfrequency band and to a third frequency band. The first frequency bandis different from the second frequency band and from the third frequencyband. A first frequency division duplex (FDD) communication path can beoperated in the second frequency band. A second FDD communication pathcan be operated in the third frequency band. Signals are transmittedover the TDD communication path via a second portion of the firstfrequency band that is different from the first portion of the firstfrequency band.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a wireless communication system,according to an embodiment.

FIG. 2 is a schematic representation of coexisting mobile devices,according to embodiments.

FIG. 3 is a diagram illustrating an asymmetric time division duplexing(TDD) scheme in AWS-3 flexible use spectrum, according to an embodiment.

FIG. 4 is a diagram illustrating aspects of an asymmetric TDDcommunication scheme for use in the AWS-3 portion of the wirelessspectrum, according to an embodiment.

FIGS. 5A-5B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent frequency division duplexing (FDD) schemes,according to embodiments.

FIGS. 6A-6B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent FDD schemes, according to embodiments.

FIGS. 7A-7B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent FDD and synchronous TDD schemes, according toembodiments.

FIGS. 7C-7D are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent FDD and synchronous TDD schemes, according toembodiments.

FIGS. 8A-8B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent synchronous TDD and asynchronous TDD schemes,according to embodiments.

FIGS. 9A-9B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent synchronous TDD and temporally-asymmetric TDDschemes, according to embodiments.

FIGS. 10A-10B are each a diagram depicting time and frequency aspects ofa TDD scheme with adjacent temporally-asymmetric TDD schemes, accordingto embodiments.

FIGS. 11A-11B are each a diagram depicting time and frequency aspects ofa TDD scheme with adjacent temporally-asymmetric TDD schemes, accordingto embodiments.

FIGS. 12A-12B are each a diagram depicting time and frequency aspects ofa TDD scheme with adjacent FDD and broadcast schemes, according toembodiments.

FIGS. 13-15 are flow charts illustrating a method for a TDD scheme,according to embodiments.

DETAILED DESCRIPTION

The devices and methods described herein are generally related towireless communication systems. For example, the devices and methods aresuitable for use in cellular (terrestrial) communication systems,satellite communication systems, and/or hybrid satellite and terrestrial(satellite/terrestrial) communication systems, such as a MobileSatellite Services (MSS) system with an Ancillary Terrestrial Component(ATC). An example of such a hybrid satellite/terrestrial communicationsystem is described in U.S. patent application Ser. No. 11/797,048 toZufall et, al., the disclosure of which is incorporated herein byreference in its entirety. An MSS MSS/ATC system can use one or moresatellites to support a wide geographic coverage of mobile satelliteinteractive (i.e., bidirectional) services. For example, a portion ofthe 2 GHz spectrum allocated for MSS satellite communications can beused to provide effective service coverage to rural and remote areas.Along with the MSS network, the land-based ATC network can facilitateservice penetration in urban and suburban areas through effectivesatellite and terrestrial frequency reuse.

In one or more embodiments, a method associated with terrestrial,satellite, and/or hybrid satellite/terrestrial wireless communicationsystems includes receiving and transmitting signals over an asymmetrictime division duplex (TDD) communication path. Signals are received overthe asymmetric TDD communication path via a first portion of a firstfrequency band. The first frequency band is adjacent to a secondfrequency band and to a third frequency band. The first frequency bandis different from the second frequency band and from the third frequencyband. The first frequency band, the second frequency band, and the thirdfrequency band can be mutually exclusive. A first frequency divisionduplex (FDD) communication path can be operated in the second frequencyband. A second FDD communication path can be operated in the thirdfrequency band. Signals are transmitted over the TDD communication pathvia a second portion of the first frequency band that is different fromthe first portion of the first frequency band.

It is noted that, as used in this written description and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example, theterm “a frequency” is intended to mean a single frequency or acombination of frequencies. Similarly, the term “a time slot” isintended to mean, for example, a single time slot or more than one timeslot.

FIG. 1 is a schematic representation of a wireless communication system100, according to an embodiment. The wireless communication system 100is configured to provide next generation wireless communication servicesand applications, including interactive services, for example. Thewireless communication system 100 includes a terrestrial antenna 140 anda mobile device 110. In some embodiments, the wireless communicationsystem 100 can include at least one of a satellite 130 and a broadcastantenna 120. In some embodiments, the wireless communication system 100can include multiple terrestrial antennas, multiple satellites, and/ormultiple broadcast antennas, for example.

The terrestrial antenna 140 is configured to communicate multicastand/or interactive data with the mobile device 110 via a terrestrialcommunication path, channel, or link, for example, which includes adownlink portion 142 and/or an uplink portion 144. In this example, thedownlink portion 142 refers to the portion of the terrestrialcommunication path in which data or information flows from theterrestrial antenna 140 to the mobile device 110. The terrestrialantenna 140 is thus configured to send, transmit, or transfer data tothe mobile device 110 via the downlink portion 142 of the terrestrialcommunication path, while the mobile device 110 is configured to receivedata at downlink portion 142. The uplink portion 144 refers to a portionof the terrestrial communication path in which data or information flowsfrom the mobile device 110 to the terrestrial antenna 140. The mobiledevice 110 is thus configured to send, transmit, or transfer data to theterrestrial antenna 140 via the uplink portion 144 of the terrestrialcommunication path, while the terrestrial antenna 140 is configured toreceive at uplink portion 144. The terrestrial antenna 140 can beassociated with a wireless base station used, for example, in cellularor like communication systems. In some embodiments, the downlink portion142 of the terrestrial communication path and the uplink portion 144 ofthe terrestrial communication path operate over the same frequency band.In other embodiments, the downlink portion 142 of the terrestrialcommunication path operates over a first frequency band and the uplinkportion 144 of the terrestrial communication path operates over a secondfrequency band different from the first frequency band.

The terrestrial antenna 140 is configured to communicate with the mobiledevice 110 via the terrestrial communication path, for example, by usinga duplexing scheme such as a TDD scheme, an FDD scheme, and/or a hybridTDD/FDD scheme. The terrestrial antenna 140 is thus configured toestablish and/or operate an asymmetric TDD communication scheme with themobile device 110 via the terrestrial communication path. An asymmetricTDD communication scheme refers to a TDD communication path, channel, orlink, for example, between the terrestrial antenna 140 and the mobiledevice 110 in which the amount of data flowing in one direction (uplinkor downlink) is larger than the amount of data flowing in the oppositedirection. For example, in interactive multimedia applications, theamount of data (e.g., video) flowing from the terrestrial antenna 140 tothe mobile device 110 is larger than the amount of data (e.g., userselections) flowing from the mobile device 110 to the terrestrialantenna 140. The amount of data flowing in a given direction can bebased on a spectrum bandwidth associated with that direction and/or atime interval associated with the flow of data in that direction. Anasymmetric TDD communication scheme may provide the asymmetry that isdesirable in many next generation services and applications without theneed for an auxiliary frequency band to increase capacity in onedirection or another.

The broadcast antenna 120 is configured to communicate with the mobiledevice 110 via a broadcast 122. In this example, data flows from thebroadcast antenna 120 to the mobile device 110. In one embodiment, thebroadcast antenna 120 can be a directional antenna and can be configuredsuch that the broadcast 122 occurs in a particular direction. In anotherembodiment, the broadcast antenna 120 can be an omni-directional antennaand can be configured such that the broadcast 122 occurs uniformly inevery direction.

The satellite 130 is configured to communicate multicast and/orinteractive data with the mobile device 110 via a satellitecommunication path, channel, or link, for example, which includes adownlink portion 132 and/or an uplink portion 134. In this example, thedownlink portion 132 refers to the portion of the satellitecommunication path in which data or information flows from the satellite130 to the mobile device 110. The satellite 130 is thus configured tosend, transmit, or transfer data (e.g., video content) to the mobiledevice 110 via the downlink portion 132 of the satellite communicationpath, while the mobile device 110 is configured to receive data from thesatellite 130 via that downlink portion 132. The uplink portion 134refers to a portion of the satellite communication path in which data orinformation flows from the mobile device 110 to the satellite 130. Themobile device 110 is thus configured to send, transmit, or transfer data(e.g., interactive data) to the satellite 130 via the uplink portion 134of the satellite communication path, while the satellite 130 isconfigured to receive data from the mobile device 110 via that uplinkportion 134. In some embodiments, the downlink portion 132 of thesatellite communication path and the upstream portion 134 of thesatellite communication path operate over the same frequency band. Inother embodiments, the downlink portion 132 of the satellitecommunication path operates over a first frequency band and the upstreamportion 134 of the satellite communication path operates over a secondfrequency band different from the first frequency band.

The satellite 130 is configured to communicate with the mobile device110 via the satellite communication path, for example, by using aduplexing scheme such as a TDD scheme, an FDD scheme, and/or a hybridTDD/FDD scheme. The satellite 130 is configured to establish and/oroperate an asymmetric TDD communication scheme with the mobile device110 via the satellite communication path. For example, in interactivetravel assistance applications, the amount of data (e.g., navigationdata) flowing from the satellite 130 to the mobile device 110 is largerthan the amount of data (e.g., user queries) flowing from the mobiledevice 110 to the satellite 130. The amount of data flowing in a givendirection can be based on a spectrum bandwidth associated with thatdirection and/or a time interval associated with that direction.

In some embodiments, the satellite 130 and the terrestrial antenna 140can be used in a hybrid satellite/terrestrial communication system tocommunicate with the mobile device 110. For example, the satellite 130can be configured to communicate with the terrestrial antenna 140 suchthat data can flow from the satellite 130 to the mobile device 110 viathe terrestrial antenna 140. In this example, the satellite 130 can beconfigured to send data to the terrestrial antenna 140 via a downlinkportion of a given satellite communication path (not shown) with theterrestrial antenna 140. The terrestrial antenna 140 can be configuredto send the data received from the satellite 130 to the mobile device110 via the downlink portion 142 of the terrestrial communication path.In another example, the terrestrial antenna 140 can be configured tocommunicate with the satellite 130 via a network (not shown) and/or aground station (not shown).

The mobile device 110 can include a handheld device, a laptop, and/or anin-vehicle system, for example. The mobile device 110 is configured tocommunicate with the satellite 130 and/or the terrestrial antenna 140.For example, the mobile device 110 can be configured to communicate withthe satellite 130 via an asymmetric TDD communication scheme (e.g., TDDdownlink and TDD uplink) over a satellite communication path. In anotherexample, the mobile device 110 can be configured to communicate with theterrestrial antenna 140 via an asymmetric TDD communication scheme(e.g., TDD downlink and TDD uplink) over a terrestrial communicationpath. The mobile device 110 can also be configured to receive broadcastdata from the broadcast antenna 120. The functionality of the mobiledevice 110 can be software-based (e.g., set of instructions executableat a processor, software code) and/or hardware-based (e.g., circuitsystem, processor, application-specific integrated circuit (ASIC), fieldprogrammable gate array (FPGA)). The mobile device 110 can include aprocessor and a related processor-readable medium having instructions orcomputer code thereon for performing various processor-implementedoperations. Such processors can be implemented as hardware modules suchas embedded microprocessors, microprocessors as part of a computersystem, Application-Specific Integrated Circuits (“ASICs”), andProgrammable Logic Devices (“PLDs”). Such processors can also beimplemented as one or more software modules in programming languages asJava, C++, C, assembly, a hardware description language, or any othersuitable programming language.

A processor according to some embodiments of the mobile device 110includes media and computer code (also can be referred to as code)specially designed and constructed for the specific purpose or purposes.Examples of processor-readable media include, but are not limited to:magnetic storage media such as hard disks, floppy disks, and magnetictape; optical storage media such as Compact Disc/Digital Video Discs(“CD/DVDs”), Compact Disc-Read Only Memories (“CD-ROMs”), andholographic devices; magneto-optical storage media such as opticaldisks, and read-only memory (“ROM”) and random-access memory (“RAM”)devices. Examples of computer code include, but are not limited to,micro-code or micro-instructions, machine instructions, such as producedby a compiler, and files containing higher-level instructions that areexecuted by a computer using an interpreter. For example, an embodimentof the mobile device 110 may be implemented using Java, C++, or otherobject-oriented programming language and development tools. Additionalexamples of computer code include, but are not limited to, controlsignals, encrypted code, and compressed code.

In some embodiments, at least a portion of the wireless communicationsystem 100 can be pre-configured to support an asymmetric TDDcommunication scheme. In other embodiments, at least a portion of thewireless communication system 100 can be dynamically configured (e.g.,after deployment) to support an asymmetric TDD communication scheme.

FIG. 2 is a schematic representation showing mobile devices 210, 220,and 230 operating in an area 200, according to embodiments. The mobiledevice 220 is configured to communicate with a given wirelesscommunication system (not shown), such as the wireless communicationsystem 100 described above with respect to FIG. 1. The mobile device 220can communicate with that wireless communication system via anasymmetric TDD communication scheme. For example, the mobile device 220can communicate via an uplink portion 224 and a downlink portion 222 ofan asymmetric TDD communication scheme associated with a particularfrequency band (frequency band 1).

The mobile device 210 and the mobile device 230 are each configured tocommunicate with a wireless communication system (not shown) via acommunication path that includes one of multiple communication methodssuch as an FDD communication scheme, a TDD communication schemesynchronous with the asymmetric TDD communication scheme associated withthe mobile device 220, a TDD communication scheme asynchronous with theasymmetric TDD communication scheme associated with the mobile device220, a temporally-asymmetric TDD communication scheme, or a broadcast,for example. In some embodiments, the mobile device 210 can communicatewith its associated wireless communication system via a communicationpath having an uplink portion 214 and a downlink portion 212. Each ofthe uplink portion 214 and the downlink portion 212 of the communicationpath is associated with a frequency band 2. Similarly, the mobile device230 can communicate with its associated wireless communication systemvia a communication path having an uplink portion 234 and a downlinkportion 232. Each of the uplink portion 234 and downlink portion 2232 isassociated with a frequency band 3. In some embodiments, the frequencyband 2 and/or the frequency band 3 can include multiple frequency bandsor frequency subbands.

The frequency bands 1, 2, and 3 can be adjacent (i.e., adjoining orneighboring) frequency bands. For example, frequency band 1 can beadjacent to frequency band 2 and adjacent to frequency band 3. Thefrequency bands 1, 2, and 3 can be mutually exclusive frequency bands,for example. In some embodiments, the frequency band 1 can be associatedwith a flexible-use spectrum, for example.

The mobile devices 220 and 210 are configured to coexist in the area 200such that minimal (if any) interference occurs between the asymmetricTDD communication scheme being used by the mobile device 220 (andassociated with frequency band 1) and the communication method beingused by the mobile device 210 (and associated with frequency band 2).Similarly, the mobile devices 220 and 230 are configured to coexist inthe area 200 such that minimal (if any) interference occurs between theasymmetric TDD communication scheme being used by the mobile device 220(and associated with frequency band 1) and the communication methodbeing used by the mobile device 230 (and associated with frequency band3). The size of the area 200 may be associated with the minimum distancebetween the mobile device 220 and the mobile device 210, and/or theminimum distance between the mobile device 220 and the mobile device 230such that the mobile devices 210, 220, and/or 230 can effectivelyoperate (i.e., coexist) without interfering with each other.

FIG. 3 is a diagram illustrating an asymmetric TDD scheme in an advancedwireless services (AWS) spectrum, according to an embodiment. Thewireless spectrum 300 is a portion of the radio frequency spectrum thatincludes a portion 310 (AWS-1 F Block), a portion 320 (AWS-3), a portion330 (J Block), a portion 340 (MSS-1), and a portion 350 (MSS-2). TheAWS-1 and AWS-3 are each a portion of an AWS frequency band planassociated with next generation voice and data services andapplications. The AWS-1 includes multiple frequency blocks, such asblocks A, B, C, D, E, and F. Each frequency block has an associatedmobile frequency band and base frequency band. The portion 310 of thewireless spectrum 300 is associated with the base frequency band of theAWS-1 F block of the AWS frequency band plan. The AWS-1 F block includesfrequencies from about 1745 megahertz (MHz) to about 2155 MHz and isused for downlink communication via a downlink portion 312 of acommunication path between, for example, a base station (e.g.,terrestrial antenna) and a mobile device. The AWS-1 F block is shown asbeing adjacent to the AWS-3 portion of the AWS frequency band plan.

The J block is a frequency band being proposed for use with an AWS-2portion (not shown) of the AWS frequency band plan. The J block includesfrequencies from about 2175 MHz to about 2180 MHz. The J block is shownas being adjacent to the AWS-3 portion of the AWS frequency band planand adjacent to the MSS-1 portion of the wireless spectrum 300. The Jblock is used for downlink communication via a downlink portion 332 of acommunication path between, for example, a terrestrial antenna and amobile device.

Each of the MSS-1 and MSS-2 is a portion of the wireless spectrum 300that is used for mobile satellite services systems. The MSS-1 portion ofthe wireless spectrum 300 is associated with a frequency band thatincludes frequencies from about 2180 MHz to about 2190 MHz. The MSS-2portion of the wireless spectrum 300 is associated with a frequency bandthat includes frequencies from about 2190 MHz to about 2200 MHz. Each ofthe MSS-1 and MSS-2 portions of the wireless spectrum 300 can be used inhybrid satellite/terrestrial wireless communication systems, forexample. The MSS-1 portion of the wireless spectrum 300 is used fordownlink communication via a downlink portion 342 of a communicationpath between, for example, a base station or a satellite, and a mobiledevice. The MSS-2 portion of the wireless spectrum 300 is used fordownlink communication via a downlink portion 352 of a communicationpath between, for example, a base station or a satellite, and a mobiledevice. The MSS-1 portion of the wireless spectrum 300 is shown as beingadjacent to the J block and adjacent to the MSS-2 portion of thewireless spectrum 300. The MSS-2 portion of the wireless spectrum 300 isshown as being adjacent to the MSS-1 portion of the wireless spectrum300.

The AWS-3 portion of the AWS frequency band plan is being proposed forflexible-use spectrum services and applications. The AWS-3 portion ofthe AWS frequency band plan can be used for services and applicationsthat use different communication methods. For example, the AWS-3 portionof the AWS frequency band plan can be used for an asymmetric TDDcommunication scheme via a communication path between, for example, abase station or a satellite, and a mobile device. The communication pathassociated with the asymmetric TDD communication scheme includes adownlink portion 322 and an uplink portion 324. Because the AWS-3portion of the AWS frequency band plan is adjacent to the AWS-1 F blockand the J block, it is desirable that the downlink portion 322 and theuplink portion 324 be configured such that minimal (if any) interferenceoccurs between the frequency band associated with the AWS-3 portion ofthe AWS frequency band plan and the frequency bands associated with theAWS-1 F block and the J block.

FIG. 4 is a diagram illustrating aspects of an asymmetric TDDcommunication scheme for use in the AWS-3 portion of the wirelessspectrum 300 described above with respect to FIG. 3, according to anembodiment. The asymmetric TDD communication scheme allocates or assignsfrequencies from about 2160 MHz to about 2170 MHz to a first portion 410of a frequency band 440 and associated with a frequency band 430. Theasymmetric TDD communication scheme also allocates or assignsfrequencies from about 2155 MHz to about 2175 MHz to a second portion420 associated with the frequency band 440. The first portion 410 isdifferent from the second portion 420 of the asymmetric TDDcommunication scheme. For example, a spectrum bandwidth associated withthe frequency band 440 of the second portion 420 is larger than aspectrum bandwidth associated with the frequency band 420 of the firstportion 410.

The first portion 410 is associated with an uplink portion or uplinkcommunication portion (I) of the asymmetric TDD communication scheme.The first portion 410 has an uplink time interval or uplink time slot,T_(U), associated with the interval between time instances t₁ and t₂.The second portion 420 is associated with a downlink portion or downlinkcommunication portion (↓) of the asymmetric TDD communication scheme.The second portion 420 has a downlink time interval or downlink timeslot, T_(D), associated with the interval between time instances t₀ andt₁. In some embodiments, the interval between time instances t₁ and t₂can have substantially the same duration as the interval between timeinstances t₀ and t₁. In other embodiments, the interval between timeinstances t₁ and t₂ can have a different duration than the duration ofthe interval between time instances t₀ and t₁.

Asymmetric data flow in the TDD communication scheme occurs when atime-bandwidth product associated with the first portion 410 isdifferent from a time-bandwidth product associated with the secondportion 420. The time-bandwidth product associated with the firstportion 410 refers to the product of T_(U) and the spectrum bandwidthassociated with the frequency band 430. The time-bandwidth productassociated with the first portion 410 is proportional to the amount ofdata that can flow in the direction of the first portion 410. Thetime-bandwidth product associated with the second portion 420 refers tothe product of T_(D) and the spectrum bandwidth associated with thefrequency band 440. The time-bandwidth product associated with thesecond portion 420 is proportional to the amount of data that can flowin the direction of the second portion 420. When T_(U) and T_(D) aresubstantially the same, the amount of data flow in a given direction isproportional to the spectrum bandwidth of the frequency band associatedwith that direction. In this example, when T_(U) and T_(D) aresubstantially the same, the amount of data flow is larger in thedownlink direction associated with the second portion 420 of theasymmetric TDD communication scheme than in the uplink directionassociated with the first portion 410 of the asymmetric TDDcommunication scheme.

The asymmetric TDD communication scheme also includes an uplink guardband 450 that separates the first portion 410 from a frequency band(e.g., AWS-1 F block) that is adjacent to the 2155 MHz frequency of thefrequency band 440. The asymmetric TDD communication scheme furtherincludes an uplink guard band 460 that separates the first portion 410from a frequency band (e.g., J block) that is adjacent to the 2175 MHzfrequency of the frequency band 440. The uplink guard bands 450 and 460are used to minimize or reduce the interference that can occur betweenthe downlink portions of the adjacent frequency bands and the uplinkportion of the asymmetric TDD communication scheme described in FIG. 4.

FIGS. 5A-5B are each a diagram depicting the time and frequency aspectsof a TDD scheme with adjacent FDD schemes, according to embodiments.FIG. 5A shows a diagram 500 that illustrates a first frequency band 504associated with a TDD communication path. The TDD communication path canbe symmetric or asymmetric. In some embodiments, it may be desirablethat the TDD communication path be asymmetric to be used in nextgeneration applications and services. The diagram 500 also illustrates asecond frequency band 502 associated with an uplink portion of an FDDcommunication path and a third frequency band 506 associated with adownlink portion of an FDD communication path. The second frequency band502 and the third frequency band 506 need not (but can) be paired FDDfrequency bands associated with the same FDD communication path.

The first frequency band 504 is associated with a spectrum bandwidththat includes frequencies in the range f₁ to f₄. The second frequencyband 502 is associated with a spectrum bandwidth that includesfrequencies in the range f₀ to f₁. The third frequency bandwidth 506 isassociated with a spectrum bandwidth that includes frequencies in therange f₄ to f₅. The first frequency band 504 is adjacent to the secondfrequency band 502 (e.g., at f₁). The first frequency band 504 isadjacent to the third frequency band 506 (e.g., at f₄). The firstfrequency band 504, the second frequency band 502, and the thirdfrequency band 506 can be mutually exclusive frequency bands. In someembodiments, the first frequency band 504, the second frequency band502, and the third frequency band 506 are wireless frequency bands.

The first frequency band 504 includes a first portion 510 that hasallocated or assigned a spectrum bandwidth including frequencies in therange f₁ to f₃. The first frequency band 504 includes a second portion512 that has allocated or assigned a spectrum bandwidth includingfrequencies in the range f₂ to f₄. The first portion 510 of the firstfrequency band 504 is different from the second portion 512 of the firstfrequency band 504 and overlaps the second portion 512 of the firstfrequency band 504. The spectrum bandwidth associated with the firstportion 510 of the first frequency band 504 can be different (or thesame) from the spectrum bandwidth associated with the second portion 512of the first frequency band 504.

The first portion 510 of the first frequency band 504 is associated withan uplink portion or uplink communication portion of the TDDcommunication path. The first portion 510 has an uplink time interval oruplink time slot, T_(U), associated with the interval between timeinstances t₁ and t₂. The second portion 512 of the first frequency band504 is associated with a downlink portion or downlink communicationportion of the TDD communication path. The second portion 512 has adownlink time interval or downlink time slot, T_(D), associated with theinterval between time instances t₀ and t₁.

When the time-bandwidth product associated with the first portion 510 ofthe first frequency band 504 is substantially the same as thetime-bandwidth product associated with the second portion 512 of thefirst frequency band 504, the TDD communication path associated with thefirst frequency band 504 operates as a symmetric TDD communication path.The time-bandwidth product associated with the first portion 510 of thefirst frequency band 504 refers to the product of T_(U) and the spectrumbandwidth between frequencies f₁ and f₃. The time-bandwidth productassociated with the second portion 512 of the first frequency band 504refers to the product of T_(D) and the spectrum bandwidth betweenfrequencies f₂ and f₄. When the time-bandwidth product associated withthe first portion 510 of the first frequency band 504 is different fromthe time-bandwidth product associated with the second portion 512 of thefirst frequency band 504, the TDD communication path associated with thefirst frequency band 504 operates as an asymmetric TDD communicationpath.

FIG. 5A shows the first portion 510 of the first frequency band 504 asbeing adjacent to the second frequency band 502 and separate from thethird frequency band 506 by an uplink guard band 516. Because the firstportion 510 of the first frequency band 504 and the uplink portion ofthe FDD communication path associated with the second frequency band 502are both either transmitting or receiving signals in a same direction,no guard band may be desirable between the first portion 510 of thefirst frequency band 504 and the second frequency band 502 given thatminimal (if any) interference occurs. On the other hand, the firstportion 510 of the first frequency band 504 and the downlink portion ofthe FDD communication link associated with the third frequency band 506may need a guard band (e.g., uplink guard band 516) because they areeither transmitting or receiving signals in opposite directions, whichmay result in significant levels of interference.

Similarly, the second portion 512 of the first frequency band 504 isshown as being adjacent to the third frequency band 506 and separatefrom the second frequency band 502 by a downlink guard band 514. Becausethe second portion 512 of the first frequency band 504 and the downlinkportion of the FDD communication path associated with the thirdfrequency band 506 are both either transmitting or receiving signals ina same direction, no guard band may be desirable given that minimal (ifany) interference occurs between the second portion 512 of the firstfrequency band 504 and the third frequency band 506. On the other hand,the second portion 512 of the first frequency band 504 and the uplinkportion of the FDD communication path associated with the secondfrequency band 502 may need a guard band (e.g., downlink guard band 514)because they are either transmitting or receiving signals in oppositedirections, which may result in significant levels of interference. Theuplink guard band 516 and the downlink guard band 514 need not (but can)have the same spectrum bandwidth.

FIG. 5B shows a diagram 520 that illustrates a first frequency band 524associated with a TDD communication path. The diagram 520 alsoillustrates a second frequency band 522 associated with a downlinkportion of an FDD communication path and a third frequency band 526associated with an uplink portion of an FDD communication path. Thesecond frequency band 522 and the third frequency band 526 need not (butcan) be paired FDD frequency bands associated with the same FDDcommunication path.

The first frequency band 524, the second frequency band 522, and thethird frequency band 526 are similar to the first frequency band 504,the second frequency band 502, and the third frequency band 506described above with respect to FIG. 5A. The first frequency band 524includes a first portion 530 that has allocated or assigned a spectrumbandwidth including frequencies in the range f₂ to f₄. The firstfrequency band 524 includes a second portion 532 that has allocated orassigned a spectrum bandwidth including frequencies in the range f₁ tof₃. The first portion 530 of the first frequency band 524 is differentfrom the second portion 532 of the first frequency band 524 and overlapsthe second portion 532 of the first frequency band 524. The spectrumbandwidth associated with the first portion 530 of the first frequencyband 524 can be different (or the same) from the spectrum bandwidthassociated with the second portion 532 of the first frequency band 524.

The first portion 530 of the first frequency band 524 is associated withan uplink portion of the TDD communication path and has an associateduplink time slot, T_(U), described above with respect to FIG. 5A. Thesecond portion 532 of the first frequency band 524 is associated with adownlink portion of the TDD communication path and has an associateddownlink time slot, T_(D), also described above with respect to FIG. 5A.The TDD communication path associated with the first frequency 524 canbe symmetric or asymmetric based on the time-bandwidth productassociated with the first portion 530 of the first frequency band 524and the time-bandwidth product associated with the second portion 532 ofthe first frequency band 524.

FIG. 5B shows the first portion 530 of the first frequency band 524 asbeing adjacent to the third frequency band 526 and separate from thesecond frequency band 524 by an uplink guard band 534. The first portion530 of the first frequency band 524 and the downlink portion of the FDDcommunication path associated with the second frequency band 524 mayneed a guard band because they are either transmitting or receivingsignals in opposite directions, which may result in significant levelsof interference.

Similarly, the second portion 532 of the first frequency band 524 isshown as being adjacent to the second frequency band 522 and separatefrom the third frequency band 526 by a downlink guard band 536. Thesecond portion 532 of the first frequency band 524 and the uplinkportion of the FDD communication path associated with the thirdfrequency band 526 may need a guard band because they are eithertransmitting or receiving signals in opposite directions, which mayresult in significant levels of interference. The uplink guard band 534and the downlink guard band 536 need not (but can) have the samespectrum bandwidth.

FIGS. 6A-6B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent FDD schemes, according to other embodiments.FIG. 6A shows a diagram 600 that illustrates a first frequency band 604associated with a TDD communication path. The diagram 600 alsoillustrates a second frequency band 602 associated with an uplinkportion of an FDD communication path and a third frequency band 606associated with an uplink portion of an FDD communication path differentfrom the FDD communication path associated with the second frequencyband 602.

The first frequency band 604 is associated with a spectrum bandwidththat includes frequencies in the range f₁ to f₄. The second frequencyband 602 is associated with a spectrum bandwidth that includesfrequencies in the range f₀ to f₁. The third frequency bandwidth 606 isassociated with a spectrum bandwidth that includes frequencies in therange f₄ to f₅. The first frequency band 604 is adjacent to the secondfrequency band 602 (e.g., at f₁). The first frequency band 604 isadjacent to the third frequency band 606 (e.g., at f₄). The firstfrequency band 604, the second frequency band 602, and the thirdfrequency band 606 can be mutually exclusive frequency bands. In someembodiments, the first frequency band 604, the second frequency band602, and the third frequency band 606 are wireless frequency bands.

The first frequency band 604 includes a first portion 610 that hasallocated or assigned a spectrum bandwidth including frequencies in therange f₁ to f₄. The first frequency band 604 includes a second portion612 that has allocated or assigned a spectrum bandwidth includingfrequencies in the range f₂ to f₃. The first portion 610 of the firstfrequency band 604 is different from the second portion 612 of the firstfrequency band 604 and overlaps the second portion 612 of the firstfrequency band 604. The spectrum bandwidth associated with the firstportion 610 of the first frequency band 604 is different from thespectrum bandwidth associated with the second portion 612 of the firstfrequency band 604.

The first portion 610 of the first frequency band 604 is associated withan uplink portion or uplink communication portion of the TDDcommunication path. The first portion 610 has an uplink time interval oruplink time slot, T_(U), associated with the interval between timeinstances t₁ and t₂. The second portion 612 of the first frequency band604 is associated with a downlink portion or downlink communicationportion of the TDD communication path. The second portion 612 has adownlink time interval or downlink time slot, T_(D), associated with theinterval between time instances t₀ and t₁.

When the time-bandwidth product associated with the first portion 610 ofthe first frequency band 604 is substantially the same as thetime-bandwidth product associated with the second portion 612 of thefirst frequency band 604, the TDD communication path associated with thefirst frequency band 604 operates as a symmetric TDD communication path.When the time-bandwidth product associated with the first portion 610 ofthe first frequency band 604 is different from the time-bandwidthproduct associated with the second portion 612 of the first frequencyband 604, the TDD communication path associated with the first frequencyband 604 operates as an asymmetric TDD communication path. Because thespectrum bandwidth associated with the first portion 610 of the firstfrequency band 604 is different from the spectrum bandwidth associatedwith the second portion 612 of the first frequency band 604, when thetime intervals associated with the time slots T_(U) and T_(D) are thesame, the TDD communication path associated with the first frequencyband 604 operates as an asymmetric TDD communication path.

FIG. 6A shows the first portion 610 of the first frequency band 604 asbeing adjacent to the second frequency band 602 and to the thirdfrequency band 606. Because the first portion 610 of the first frequencyband 604, the uplink portion of the FDD communication path associatedwith the second frequency band 602, and the uplink portion of the FDDcommunication path associated with the second frequency band 606 areeither transmitting or receiving signals in a same direction, no guardband may be desirable given that minimal (if any) interference mayoccur.

The second portion 612 of the first frequency band 604 is shown as beingseparated from the second frequency band 602 by a downlink guard band614 and separate from the third frequency band 606 by a downlink guardband 616. The downlink guard bands 614 and 616 may be desirable becausethe second portion 612 of the first frequency band 604, the uplinkportion of the FDD communication path associated with the secondfrequency band 602, and the uplink portion of the FDD communication pathassociated with the second frequency band 606 are either transmitting orreceiving signals in opposite directions, which may result insignificant levels of interference. The downlink guard band 614 and 616need not (but can) have the same spectrum bandwidth.

FIG. 6B shows a diagram 620 that illustrates a first frequency band 624associated with a TDD communication path. The diagram 620 alsoillustrates a second frequency band 622 associated with a downlinkportion of an FDD communication path and a third frequency band 626associated with a downlink portion of an FDD communication pathdifferent from the FDD communication path associated with the secondfrequency band 622.

The first frequency band 624, the second frequency band 622, and thethird frequency band 626 are similar to the first frequency band 604,the second frequency band 602, and the third frequency band 606described above with respect to FIG. 6A. The first frequency band 624includes a first portion 630 that has allocated or assigned a spectrumbandwidth including frequencies in the range f₂ to f₃. The firstfrequency band 624 includes a second portion 632 that has allocated orassigned a spectrum bandwidth including frequencies in the range f₁ tof₄. The first portion 630 of the first frequency band 624 is differentfrom the second portion 632 of the first frequency band 624 and overlapsthe second portion 632 of the first frequency band 624. The spectrumbandwidth associated with the first portion 630 of the first frequencyband 624 is different from the spectrum bandwidth associated with thesecond portion 632 of the first frequency band 624.

The first portion 630 of the first frequency band 624 is associated withan uplink portion of the TDD communication path and has an associateduplink time slot, T_(U), described above with respect to FIG. 6A. Thesecond portion 632 of the first frequency band 624 is associated with adownlink portion of the TDD communication path and has an associateddownlink time slot, T_(D), also described above with respect to FIG. 6A.The TDD communication path associated with the first frequency 624 canbe symmetric or asymmetric based on the time-bandwidth productassociated with the first portion 630 of the first frequency band 624and the time-bandwidth product associated with the second portion 632 ofthe first frequency band 624. Because the spectrum bandwidth associatedwith the first portion 630 of the first frequency band 624 is differentfrom the spectrum bandwidth associated with the second portion 632 ofthe first frequency band 624, when the time intervals associated withthe time slots T_(U) and T_(D) are the same, the TDD communication pathassociated with the first frequency band 624 operates as an asymmetricTDD communication path.

FIG. 6B shows the first portion 630 of the first frequency band 624 asbeing separated from the second frequency band 622 by an uplink guardband 634 and separate from the third frequency band 626 by an uplinkguard band 636. The uplink guard bands 634 and 636 need not (but can)have the same spectrum bandwidth. The second portion 632 of the firstfrequency band 624 is shown as being adjacent to the second frequencyband 622 and adjacent to the third frequency band 626.

FIGS. 7A-7B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent FDD and synchronous TDD schemes, according toembodiments. FIG. 7A shows a diagram 700 that illustrates a firstfrequency band 704 associated with a TDD communication path. The diagram700 illustrates a second frequency band 702 associated with a TDDcommunication path that is synchronized to the TDD communication path inthe first frequency band 704. The diagram 700 also illustrates a thirdfrequency band 706 associated with an uplink portion of an FDDcommunication path.

The first frequency band 704 is associated with a spectrum bandwidththat includes frequencies in the range f₁ to f₃. The second frequencyband 702 is associated with a spectrum bandwidth that includesfrequencies in the range f₀ to f₁. The third frequency bandwidth 706 isassociated with a spectrum bandwidth than includes frequencies betweenfrequencies f₃ and f₄. The first frequency band 704 is adjacent to thesecond frequency band 702 (e.g., at f₁). The first frequency band 704 isalso adjacent to the third frequency band 706 (e.g., at f₃). The firstfrequency band 704, the second frequency band 702, and the thirdfrequency band 706 can be mutually exclusive frequency bands. In someembodiments, the first frequency band 704, the second frequency band702, and the third frequency band 706 are wireless frequency bands.

The first frequency band 704 includes a first portion 710 that hasallocated or assigned a spectrum bandwidth including frequencies in therange f₁ to f₃. The first frequency band 704 includes a second portion712 that has allocated or assigned a spectrum bandwidth includingfrequencies in the range f₁ to f₂. The first portion 710 of the firstfrequency band 704 is different from the second portion 712 of the firstfrequency band 704 and overlaps the second portion 712 of the firstfrequency band 704. The spectrum bandwidth associated with the firstportion 710 of the first frequency band 704 is different from thespectrum bandwidth associated with the second portion 712 of the firstfrequency band 704.

The first portion 710 of the first frequency band 704 is associated withan uplink portion or uplink communication portion of the TDDcommunication path. The first portion 710 has an uplink time interval oruplink time slot, T_(U), associated with the interval between timeinstances t₁ and t₂. The second portion 712 of the first frequency band704 is associated with a downlink portion or downlink communicationportion of the TDD communication path. The second portion 712 has adownlink time interval or downlink time slot, T_(D), associated with theinterval between time instances t₀ and t₁.

When the time-bandwidth product associated with the first portion 710 ofthe first frequency band 704 is substantially the same as thetime-bandwidth product associated with the second portion 712 of thefirst frequency band 704, the TDD communication path associated with thefirst frequency band 704 operates as a symmetric TDD communication path.When the time-bandwidth product associated with the first portion 710 ofthe first frequency band 704 is different from the time-bandwidthproduct associated with the second portion 712 of the first frequencyband 704, the TDD communication path associated with the first frequencyband 704 operates as an asymmetric TDD communication path.

FIG. 7A shows the first portion 710 of the first frequency band 704 asbeing adjacent to the second frequency band 702. The synchronized orsynchronous TDD communication path in the second frequency band 702 hasan uplink portion (not shown) and a downlink portion (not shown) thatoperate at substantially the same time intervals (i.e., synchronously)as the time intervals T_(U) and T_(D) of the first portion 710 and thesecond portion 712 of the first frequency band 704, respectively. As aresult, the first portion 710 of the first frequency band 704 and thesynchronous TDD communication path associated with the second frequencyband 702 are both either transmitting or receiving signals in a samedirection and no guard band may be desirable given that minimal (if any)interference occurs between the first portion 710 of the first frequencyband 704 and the second frequency band 702.

The first portion 710 of the first frequency band 704 is also adjacentto the third frequency band 706. The first portion 710 of the firstfrequency band 704 and the uplink portion of the FDD communication pathassociated with the third frequency band 706 need no guard band becausethey are either transmitting or receiving signals in the same directionwith minimal or no interference between the frequency bands.

The second portion 712 of the first frequency band 704 is shown as beingadjacent to the second frequency band 702 and separate from the thirdfrequency band 706 by a downlink guard band 714. No guard band is neededbetween the second portion 712 of the first frequency band 704 and thesynchronous TDD communication path associated with the second frequencyband 702. The downlink guard band 704, however, is needed because thesecond portion 712 of the first frequency band 704 and the uplinkportion of the FDD communication path associated with the thirdfrequency band 706 are transmitting or receiving signals in oppositedirections.

FIG. 7B shows a diagram 720 that illustrates a first frequency band 724associated with a TDD communication path. The diagram 720 alsoillustrates a second frequency band 722 associated with an uplinkportion of an FDD communication path and a third frequency band 726associated with a synchronous TDD communication path.

The first frequency band 724, the second frequency band 722, and thethird frequency band 726 are similar to the first frequency band 704,the second frequency band 702, and the third frequency band 706described above with respect to FIG. 7A. The first frequency band 724includes a first portion 730 that has allocated or assigned a spectrumbandwidth including frequencies in the range f₁ to f₃. The firstfrequency band 724 includes a second portion 732 that has allocated orassigned a spectrum bandwidth including frequencies in the range f₂ tof₃. The first portion 730 of the first frequency band 724 is differentfrom the second portion 732 of the first frequency band 724 and overlapsthe second portion 732 of the first frequency band 724. The spectrumbandwidth associated with the first portion 730 of the first frequencyband 724 is different from the spectrum bandwidth associated with thesecond portion 732 of the first frequency band 724.

The first portion 730 of the first frequency band 724 is associated withan uplink portion of the TDD communication path and has an associateduplink time slot, T_(U), described above with respect to FIG. 7A. Thesecond portion 732 of the first frequency band 724 is associated with adownlink portion of the TDD communication path and has an associateddownlink time slot, T_(D), also described above with respect to FIG. 7A.The TDD communication path associated with the first frequency 724 canbe symmetric or asymmetric based on the time-bandwidth productassociated with the first portion 730 of the first frequency band 724and the time-bandwidth product associated with the second portion 732 ofthe first frequency band 724.

FIG. 7B shows the first portion 730 of the first frequency band 724 asbeing adjacent to the second frequency band 722 and adjacent to thethird frequency band 726. The first portion 730 of the first frequencyband 724 and the uplink portion of the FDD communication link associatedwith the second frequency band 722 need no guard band because they areeither transmitting or receiving signals in the same direction withminimal (if any) interference. Similarly, the first portion 730 of thefirst frequency band 724 and the synchronous TDD communication pathassociated with the third frequency band 726 need no guard band becausethey are synchronously transmitting or receiving signals in the samedirection.

The second portion 732 of the first frequency band 724 is shown as beingseparated from the second frequency band 722 by a downlink guard band734 and adjacent to the third frequency band 726. The second portion 732of the first frequency band 724 and the uplink portion of the FDDcommunication path associated with the second frequency band 722 mayneed a guard band because they are either transmitting or receivingsignals in opposite directions and are likely to interfere with eachother. The second portion 732 of the first frequency band 724 and thesynchronous TDD communication path associated with the third frequencyband 726 do not need a guard band because they are synchronouslytransmitting or receiving signals in the same direction

FIGS. 7C-7D are each a diagram depicting time and frequency aspects ofan asymmetric TDD scheme with adjacent FDD and synchronous TDD schemes,according other embodiments. FIG. 7C shows a diagram 740 thatillustrates a first frequency band 744 associated with a TDDcommunication path that can be symmetric or asymmetric. The diagram 740also illustrates a second frequency band 742 associated with a TDDcommunication path that is synchronized to the TDD communication path inthe first frequency band 744. The diagram 740 also illustrates a thirdfrequency band 706 associated with a downlink portion of an FDDcommunication path.

The first frequency band 744 is associated with a spectrum bandwidththat includes frequencies in the range f₁ to f₃. The second frequencyband 742 is associated with a spectrum bandwidth that includesfrequencies in the range f₀ to f₁. The third frequency bandwidth 746 isassociated with a spectrum bandwidth that includes frequencies in therange f₃ to f₄. The first frequency band 744 is adjacent to the secondfrequency band 742 (e.g., at f₁). The first frequency band 744 isadjacent to the third frequency band 746 (e.g., at f₃). The firstfrequency band 744, the second frequency band 742, and the thirdfrequency band 746 can be mutually exclusive frequency bands. In someembodiments, the first frequency band 744, the second frequency band742, and the third frequency band 746 are wireless frequency bands.

The first frequency band 744 includes a first portion 750 that hasallocated or assigned a spectrum bandwidth including frequencies in therange f₁ to f₂. The first frequency band 744 includes a second portion752 that has allocated or assigned a spectrum bandwidth includingfrequencies between frequencies f₁ and f₃. The first portion 750 of thefirst frequency band 744 is different from the second portion 752 of thefirst frequency band 744 and overlaps the second portion 752 of thefirst frequency band 744. The spectrum bandwidth associated with thefirst portion 750 of the first frequency band 744 is different from thespectrum bandwidth associated with the second portion 752 of the firstfrequency band 744.

The first portion 750 of the first frequency band 744 is associated withan uplink portion or uplink communication portion of the TDDcommunication path. The first portion 750 has an uplink time interval oruplink time slot, T_(U), associated with the interval between timeinstances t₁ and t₂. The second portion 752 of the first frequency band744 is associated with a downlink portion or downlink communicationportion of the TDD communication path. The second portion 752 has adownlink time interval or downlink time slot, T_(D), associated with theinterval between time instances t₀ and t₁.

When the time-bandwidth product associated with the first portion 750 ofthe first frequency band 744 is substantially the same as thetime-bandwidth product associated with the second portion 752 of thefirst frequency band 744, the TDD communication path associated with thefirst frequency band 744 operates as a symmetric TDD communication path.When the time-bandwidth product associated with the first portion 750 ofthe first frequency band 744 is different from the time-bandwidthproduct associated with the second portion 752 of the first frequencyband 744, the TDD communication path associated with the first frequencyband 744 operates as an asymmetric TDD communication path.

FIG. 7C shows the first portion 750 of the first frequency band 744 asbeing adjacent to the second frequency band 742. The synchronized orsynchronous TDD communication path in the second frequency band 742 hasan uplink portion (not shown) and a downlink portion (not shown) thatoperate at substantially the same time intervals (i.e., synchronously)as the time intervals T_(U) and T_(D) of the first portion 750 and thesecond portion 752 of the first frequency band 744, respectively. As aresult, the first portion 750 of the first frequency band 744 and thesynchronous TDD communication path associated with the second frequencyband 742 are both either transmitting or receiving signals in a samedirection and no guard band may be desirable given that minimal (if any)interference occurs between the first portion 750 of the first frequencyband 744 and the second frequency band 742.

The first portion 750 of the first frequency band 744 is separate fromthe third frequency band 746 by an uplink guard band 754 because thefirst portion 750 of the first frequency band 744 and the FDDcommunication path associated with third frequency band 746 aretransmitting or receiving signals in the opposite directions. The secondportion 752 of the first frequency band 744 is shown as being adjacentto the second frequency band 742 and adjacent to the third frequencyband 746.

FIG. 7D shows a diagram 760 that illustrates a first frequency band 764associated with a TDD communication path. The diagram 760 alsoillustrates a second frequency band 762 associated with a downlinkportion of an FDD communication path and a third frequency band 766associated with a synchronous TDD communication path.

The first frequency band 764, the second frequency band 762, and thethird frequency band 766 are similar to the first frequency band 744,the second frequency band 742, and the third frequency band 746described above with respect to FIG. 7C. The first frequency band 764includes a first portion 770 that has allocated or assigned a spectrumbandwidth including frequencies in the range f₂ to f₃. The firstfrequency band 764 includes a second portion 772 that has allocated orassigned a spectrum bandwidth including frequencies in the range f₁ tof₃. The first portion 770 of the first frequency band 764 is differentfrom the second portion 772 of the first frequency band 764 and overlapsthe second portion 772 of the first frequency band 764. The spectrumbandwidth associated with the first portion 770 of the first frequencyband 764 is different from the spectrum bandwidth associated with thesecond portion 772 of the first frequency band 764.

The first portion 770 of the first frequency band 764 is associated withan uplink portion of the TDD communication path and has an associateduplink time slot, T_(U), described above with respect to FIG. 7C. Thesecond portion 772 of the first frequency band 764 is associated with adownlink portion of the TDD communication path and has an associateddownlink time slot, T_(D), also described above with respect to FIG. 7C.The TDD communication path associated with the first frequency band 764can be symmetric or asymmetric based on the time-bandwidth productassociated with the first portion 770 of the first frequency band 764and the time-bandwidth product associated with the second portion 772 ofthe first frequency band 764.

FIG. 7D shows the first portion 770 of the first frequency band 764 asbeing separated from the second frequency band 762 by an uplink guardband 774. The first portion 770 of the first frequency band 764 isadjacent to the third frequency band 766. The second portion 772 of thefirst frequency band 764 is shown as being adjacent to the secondfrequency band 762 and adjacent to the third frequency band 766.

FIGS. 8A-8B are diagrams each depicting time and frequency aspects of aTDD scheme with adjacent synchronous TDD and asynchronous TDD schemes,according to embodiments. FIG. 8A shows a diagram 800 that illustrates afirst frequency band 804 associated with a TDD communication path. Thediagram 800 illustrates a second frequency band 802 associated with aTDD communication path that is asynchronous with the TDD communicationpath in the first frequency band 804. The diagram 800 also illustrates athird frequency band 806 associated with a TDD communication path thatis synchronous with the TDD communication path in the first frequencyband 804.

The first frequency band 804 is associated with a spectrum bandwidththat includes frequencies in the range f₁ to f₃. The second frequencyband 802 is associated with a spectrum bandwidth that includesfrequencies in the range f₀ to f₁. The third frequency bandwidth 806 isassociated with a spectrum bandwidth that includes frequencies in therange f₃ to f₄. The first frequency band 804 is adjacent to the secondfrequency band 802 (e.g., at f₁). The first frequency band 804 isadjacent to the third frequency band 806 (e.g., at f₃). The firstfrequency band 804, the second frequency band 802, and the thirdfrequency band 806 can be mutually exclusive frequency bands. In someembodiments, the first frequency band 804, the second frequency band802, and the third frequency band 806 are wireless frequency bands.

In this example, the first frequency band 804 includes a first portion810 that has allocated or assigned a spectrum bandwidth includingfrequencies in the range f₂ to f₃. The first frequency band 804 includesa second portion 812, which is also shown as being associated with thespectrum bandwidth that includes frequencies in the range f₂ to f₃. Thespectrum bandwidth associated with the first portion 810 of the firstfrequency band 804, however, need not be the same as the spectrumbandwidth associated with the second portion 812 of the first frequencyband 804.

The first portion 810 of the first frequency band 804 is associated withan uplink portion or uplink communication portion of the TDDcommunication path. The first portion 810 has an uplink time interval oruplink time slot, T_(U), associated with the interval between timeinstances t₃ and t₅. The second portion 812 of the first frequency band804 is associated with a downlink portion or downlink communicationportion of the TDD communication path. The second portion 812 has adownlink time interval or downlink time slot, T_(D), associated with theinterval between time instances t₁ and t₃.

When the time-bandwidth product associated with the first portion 810 ofthe first frequency band 804 is substantially the same as thetime-bandwidth product associated with the second portion 812 of thefirst frequency band 804, the TDD communication path associated with thefirst frequency band 804 operates as a symmetric TDD communication path.When the time-bandwidth product associated with the first portion 810 ofthe first frequency band 804 is different from the time-bandwidthproduct associated with the second portion 812 of the first frequencyband 844, the TDD communication path associated with the first frequencyband 844 operates as an asymmetric TDD communication path.

FIG. 8A shows the first portion 810 of the first frequency band 804 asbeing adjacent to the third frequency band 806. The synchronized orsynchronous TDD communication path in the third frequency band 806 hasan uplink portion (not shown) and a downlink portion (not shown) thatoperate at substantially the same time intervals (i.e., synchronously)as the time intervals T_(U) and T_(D) of the first portion 810 and thesecond portion 812 of the first frequency band 804, respectively. As aresult, the first portion 810 of the first frequency band 804 and thesynchronous TDD communication path associated with the third frequencyband 806 are both either transmitting or receiving signals in a samedirection and no guard band may be desirable.

The first portion 810 of the first frequency band 804 is separate fromthe second frequency band 802 by an uplink guard band 814 because thefirst portion 810 of the first frequency band 804 and the asynchronousTDD communication path associated with second frequency band 802 areoffset in time. For example, an uplink portion 820 of the asynchronousTDD communication path associated with the second frequency band 802 hasan uplink time slot or time interval between time instances t₂ and t₄.The uplink time slot associated with the uplink portion 820 of thesecond frequency band 802 is temporally offset or misaligned with theuplink time slot, T_(U), associated with the first portion 810 of thefirst frequency band 804. This temporal offset can result ininterference between the second frequency band 802 and the firstfrequency band 804 as at least a portion of the uplink portion 820 ofthe second frequency band 802 occurs during the second portion 812 ofthe first frequency band 804.

The second portion 812 of the first frequency band 804 is shown as beingadjacent to the third frequency band 806. The second portion 812 of thefirst frequency band 804 and the synchronous TDD communication pathassociated with the third frequency band 806 are both eithertransmitting or receiving signals in a same direction and no guard bandmay be desirable. The second portion 812 of the first frequency band 804is separate from the second frequency band 802 by a downlink guard band816 because the second portion 812 of the first frequency band 804 andthe asynchronous TDD communication path associated with second frequencyband 802 are offset in time. For example, a downlink portion 822 of theasynchronous TDD communication path associated with the second frequencyband 802 has a downlink time slot or time interval between timeinstances t₀ and t₂. The downlink time slot associated with the downlinkportion 822 of the second frequency band 802 is temporally offset ormisaligned with the downlink time slot, T_(D), associated with thesecond portion 812 of the first frequency band 804. This temporal offsetcan result in interference between the second frequency band 802 and thefirst frequency band 804.

FIG. 8B shows a diagram 840 that illustrates a first frequency band 844associated with a TDD communication path. The diagram 840 alsoillustrates a second frequency band 842 associated with an asynchronousTDD communication path and a third frequency band 846 associated with asynchronous TDD communication path.

The first frequency band 844, the second frequency band 842, and thethird frequency band 846 are similar to the first frequency band 804,the second frequency band 802, and the third frequency band 806described above with respect to FIG. 8A. A first portion 850 of thefirst frequency band 844 is similar to the first portion 810 of thefirst frequency band 804 described above with respect to FIG. 8A. Asecond portion 852 of the first frequency band 844 is similar to thesecond portion 812 of the first frequency band 804 described above withrespect to FIG. 8A.

FIG. 8B shows the first portion 850 of the first frequency band 844 andthe second portion 852 of the first frequency band as being adjacent tothe third frequency band 846. The first portion 850 of the firstfrequency band 844 is shown separate from the second frequency band 842by an uplink guard band 854 because the first portion 850 of the firstfrequency band 844 and the asynchronous TDD communication pathassociated with second frequency band 842 are offset or misaligned intime (i.e., unsynchronized). For example, an uplink portion 860 of theasynchronous TDD communication path associated with the second frequencyband 842 has an uplink time slot between time instances t₃ and t₅, whilethe uplink time slot, T_(U), of the first portion 850 of the firstfrequency band 844 is associated with time instances t₂ and t₄.

Similarly, the second portion 852 of the first frequency band 844 isshown separate from the second frequency band 842 by a downlink guardband 856 because the second portion 860 of the first frequency band 844and the asynchronous TDD communication path associated with secondfrequency band 842 are offset or misaligned in time. For example, adownlink portion 862 of the asynchronous TDD communication pathassociated with the second frequency band 842 has a downlink time slotbetween time instances t₁ and t₃, while the downlink time slot, T_(D),of the second portion 852 of the first frequency band 844 is associatedwith time instances t₀ and t₂.

FIGS. 9A-9B are each a diagram depicting time and frequency aspects of aTDD scheme with adjacent synchronous TDD and temporally-asymmetric TDDschemes, according to embodiments. FIG. 9A shows a diagram 900 thatillustrates a first frequency band 904 associated with a TDDcommunication path. The diagram 900 illustrates a second frequency band902 associated with a temporally-asymmetric TDD communication path. Thetemporally-asymmetric TDD communication path can refer to a TDDcommunication path having an uplink time slot duration different from adownlink time slot duration. The diagram 900 further illustrates a thirdfrequency band 906 associated with a TDD communication path that issynchronous with the TDD communication path in the first frequency band904.

The first frequency band 904 is associated with a spectrum bandwidththat includes frequencies in the range f₁ to f₃. The second frequencyband 902 is associated with a spectrum bandwidth that includesfrequencies in the range f₀ to f₁. The third frequency bandwidth 906 isassociated with a spectrum bandwidth that includes frequencies in therange f₃ to f₄. The first frequency band 904 is adjacent to the secondfrequency band 902 (e.g., at f₁). The first frequency band 904 isadjacent to the third frequency band 906 (e.g., at f₃). The firstfrequency band 904, the second frequency band 902, and the thirdfrequency band 906 can be mutually exclusive frequency bands. In someembodiments, the first frequency band 904, the second frequency band902, and the third frequency band 906 are wireless frequency bands.

The first frequency band 904 includes a first portion 910 that hasallocated or assigned a spectrum bandwidth including frequencies in therange f₂ to f₃. The first frequency band 904 includes a second portion912 that has allocated or assigned a spectrum bandwidth includingfrequencies in the range f₁ to f₃. The first portion 910 of the firstfrequency band 904 is different from the second portion 912 of the firstfrequency band 904. The spectrum bandwidth associated with the firstportion 910 of the first frequency band 904 is different from thespectrum bandwidth associated with the second portion 912 of the firstfrequency band 904.

The first portion 910 of the first frequency band 904 is associated withan uplink portion of the TDD communication path. The first portion 910has an uplink time slot, T_(U), associated with the interval betweentime instances t₁ and t₃. The second portion 912 of the first frequencyband 904 is associated with a downlink portion of the TDD communicationpath. The second portion 912 has a downlink time slot, T_(D), associatedwith the interval between time instances t₀ and t₁.

The TDD communication path associated with the first frequency 904 issymmetric when a time-bandwidth product associated with the firstportion 910 of the first frequency band 904 is substantially the same asa time-bandwidth product associated with the second portion 912 of thefirst frequency band 904. The TDD communication path associated with thefirst frequency 904 is asymmetric when the time-bandwidth productassociated with the first portion 910 of the first frequency band 904 isdifferent from the time-bandwidth product associated with the secondportion 912 of the first frequency band 904.

FIG. 9A shows the first portion 910 of the first frequency band 904 asbeing adjacent to the third frequency band 906. The synchronous TDDcommunication path in the third frequency band 906 has an uplink portion(not shown) and a downlink portion (not shown) that operate atsubstantially the same time intervals as the time intervals T_(U) andT_(D) of the first portion 910 and the second portion 912 of the firstfrequency band 904, respectively.

The first portion 910 of the first frequency band 904 is separate fromthe second frequency band 902 by an uplink guard band 914 because thefirst portion 910 of the first frequency band 904 and thetemporally-asymmetric TDD communication path associated with secondfrequency band 902 are offset in time. For example, an uplink portion920 of the temporally-asymmetric TDD communication path associated withthe second frequency band 802 has an uplink time slot or time intervalbetween time instances t₂ and t₃. The uplink time slot associated withthe uplink portion 920 of the second frequency band 902 is temporallyoffset or misaligned with the uplink time slot, T_(U), associated withthe first portion 910 of the first frequency band 904. This temporaloffset can result in interference between the second frequency band 902and the first frequency band 904.

The second portion 912 of the first frequency band 904 is shown as beingadjacent to the second frequency band 902 and adjacent to the thirdfrequency band 906. The second portion 912 of the first frequency band904 and the synchronous TDD communication path associated with the thirdfrequency band 906 are both either transmitting or receiving signals ina same direction and no guard band may be desirable. The second portion912 of the first frequency band 904 and the second frequency band 902need no guard band because the second portion 912 of the first frequencyband 904 and the temporally-asymmetric TDD communication path associatedwith second frequency band 902 are transmitting or receiving signals atthe same time. For example, a downlink portion 922 of thetemporally-asymmetric TDD communication path associated with the secondfrequency band 902 has a downlink time slot between time instances t₀and t₂. As a result, the downlink time slot associated with the downlinkportion 922 of the second frequency band 902 and the downlink time slot,T_(D), associated with the second portion 912 of the first frequencyband 904 are common over the time instances t₀ and t₁ associated withthe downlink time slot, T_(D), and no guard band may be desirable.

FIG. 9B shows a diagram 940 that illustrates a first frequency band 944associated with a TDD communication path. The diagram 940 alsoillustrates a second frequency band 942 associated with atemporally-asymmetric TDD communication path and a third frequency band946 associated with a synchronous TDD communication path.

The first frequency band 944, the second frequency band 942, and thethird frequency band 946 are similar to the first frequency band 904,the second frequency band 902, and the third frequency band 906described above with respect to FIG. 9A. The first frequency band 944has a first portion 950 associated with an uplink portion of the TDDcommunication path. The first frequency band 944 has a second portion952 associated with a downlink portion of the TDD communication path.The second frequency band 942 has a first portion 960 associated with anuplink portion of the temporally-asymmetric TDD communication path. Thesecond frequency band 942 has a second portion 962 associated with adownlink portion of the temporally-asymmetric TDD communication path.

The first portion 950 of the first frequency band 944 is shown as beingadjacent to the third frequency band 946 and adjacent to the secondfrequency band 942. The second portion 952 of the first frequency band944 is shown as being adjacent to the third frequency band 946 andseparate from the second frequency band 942 by a downlink guard band954. The downlink guard band 954 may be desirable because the uplinkportion 960 of the second frequency band 942 overlaps in time with thesecond portion 952 of the first frequency band 944 that is associatedwith the downlink portion of the TDD communication path.

FIGS. 10A-10B are each a diagram depicting time and frequency aspects ofa TDD scheme with adjacent temporally-asymmetric TDD schemes, accordingto an embodiment. FIG. 10A shows a diagram 1000 that illustrates a firstfrequency band 1004 associated with a TDD communication path. Thediagram 1000 also illustrates a second frequency band 1002 associatedwith a temporally-asymmetric TDD communication path. In this example,the temporally-asymmetric TDD communication path associated with thesecond frequency band 1002 has an uplink time slot duration that isshorter than a downlink time slot duration. For example, the uplink timeslot is between time instances t₂ and t₃ and the downlink time slot isbetween time instances t₀ and t₂. The diagram 1000 further illustrates athird frequency band 1006 associated with a temporally-asymmetric TDDcommunication path different from that of the second frequency band1002. In this example, the temporally-asymmetric TDD communication pathassociated with the third frequency band 1006 also has the same uplinktime slot duration and the same downlink time slot duration as thetemporally-asymmetric TDD communication path associated with the secondfrequency band 1002.

The first frequency band 1004 includes a first portion 1010 and a secondportion 1012. A spectrum bandwidth associated with the first portion1010 of the first frequency band 1004 is smaller than a spectrumbandwidth associated with the second portion 1012 of the first frequencyband 1004. The first portion 1010 of the first frequency band 1004 isassociated with an uplink portion of the TDD communication path. Thesecond portion 1012 of the first frequency band 1004 is associated witha downlink portion of the TDD communication path. The second frequencyband 1002 includes an uplink portion 1020 and a downlink portion 1022associated with the temporally-asymmetric TDD communication path. Thethird frequency band 1006 includes an uplink portion 1030 and a downlinkportion 1032 associated with the temporally-asymmetric TDD communicationpath.

FIG. 10A shows the first portion 1010 of the first frequency band 1004as separate from the second frequency band 1002 by an uplink guard band1014 and separate from the third frequency band 1006 by an uplink guardband 1016. The uplink guard bands 1014 and 1016 may be desirable becausethe downlink portion 1022 of the second frequency band 1002 and thedownlink portion 1032 of the third frequency band 1006 temporallyoverlap the first portion 1010 of the first frequency band 1004 that isassociated with the uplink portion of the TDD communication path suchthat interference may occur between the bands.

Similarly, the second portion 1012 of the first frequency band 1004 isshown as adjacent to the second frequency band 1002 and adjacent to thethird frequency band 1006. In this embodiment, guard bands need not beused because the second portion 1012 of the first frequency band 1004occurs during a time interval (e.g., between t₀ and t₁) that coincideswith a time interval (e.g., between t₀ and t₂) associated with thedownlink portion 1022 of the second frequency band 1002 and alsoassociated with the downlink portion 1032 of the third frequency band1006.

FIG. 10B shows a diagram 1040 that illustrates a first frequency band1044 associated with a TDD communication path. The diagram 1040 alsoillustrates a second frequency band 1042 associated with atemporally-asymmetric TDD communication path and a third frequency band1046 associated with a different temporally-asymmetric TDD communicationpath. In this example, the temporally-asymmetric TDD communication pathassociated with the second frequency band 1042 and thetemporally-asymmetric TDD communication path associated with the thirdfrequency band 1046 each has an uplink time slot duration that is longerthan a downlink time slot duration.

The first frequency band 1044, the second frequency band 1042, and thethird frequency band 1046 are similar to the first frequency band 1004,the second frequency band 1002, and the third frequency band 1006described above with respect to FIG. 10A. The first frequency band 1044has a first portion 1050 associated with an uplink portion of the TDDcommunication path. The first frequency band 1044 has a second portion1052 associated with a downlink portion of the TDD communication path.The second frequency band 1042 has a first portion 1060 associated withan uplink portion of the temporally-asymmetric TDD communication path.The second frequency band 1042 has a second portion 1062 associated witha downlink portion of the temporally-asymmetric TDD communication path.The third frequency band 1046 has a first portion 1070 associated withan uplink portion of the temporally-asymmetric TDD communication path.The third frequency band 1046 has a second portion 1072 associated witha downlink portion of the temporally-asymmetric TDD communication path.

The first portion 1050 of the first frequency band 1044 is shown asbeing adjacent to the third frequency band 1046 and adjacent to thesecond frequency band 1042. The second portion 1052 of the firstfrequency band 1044 is shown as being separated from to the thirdfrequency band 1046 by a downlink guard band 1056 and separate from thesecond frequency band 1042 by a downlink guard band 1054. The downlinkguard bands 1054 and 1056 may be desirable because the uplink portion1060 of the second frequency band 1042 and the uplink portion 1070 ofthe third frequency band 1046 each overlaps in time (e.g., between t₁and t₂) with the second portion 1052 of the first frequency band 1044that is associated with the downlink portion of the TDD communicationpath.

FIGS. 11A-11B are each a diagram depicting the time and frequencyaspects of a TDD scheme with adjacent temporally-asymmetric TDD schemes,according embodiments. FIG. 11 A shows a diagram 1100 that illustrates afirst frequency band 1104 associated with a TDD communication path. TheTDD communication path can be symmetric or asymmetric. The diagram 1100also illustrates a second frequency band 1102 associated with atemporally-asymmetric TDD communication path. In this example, thetemporally-asymmetric TDD communication path associated with the secondfrequency band 1002 has an uplink time slot duration (e.g., between t₃and t₄) that is shorter than a downlink time slot duration (e.g.,between t₀ and t₃). The diagram 1100 further illustrates a thirdfrequency band 1106 associated with a temporally-asymmetric TDDcommunication path. In this example, the temporally-asymmetric TDDcommunication path associated with the third frequency band 1106 has anuplink time slot duration (e.g., between t₁ and t₄) that is longer thana downlink time slot duration (e.g., between t₀ and t₁).

The first frequency band 1104 includes a first portion 1110 and a secondportion 1112. A spectrum bandwidth associated with the first portion1110 of the first frequency band 1104 can be the same (or different)than a spectrum bandwidth associated with the second portion 1112 of thefirst frequency band 1104. The first portion 1110 of the first frequencyband 1104 is associated with an uplink portion of the TDD communicationpath. The second portion 1112 of the first frequency band 1104 isassociated with a downlink portion of the TDD communication path. Thesecond frequency band 1102 includes an uplink portion 1120 and adownlink portion 1122 of the temporally-asymmetric TDD communicationpath. The third frequency band 1106 includes an uplink portion 1130 anda downlink portion 1132 of the temporally-asymmetric TDD communicationpath.S

FIG. 11A shows the first portion 1110 of the first frequency band 1104as separate from the second frequency band 1102 by an uplink guard band1114 and adjacent to the third frequency band 1106. The uplink guardband 1114 may be desirable because the downlink portion 1122 of thesecond frequency band 1102 temporally overlaps the first portion 1110 ofthe first frequency band 1104 that is associated with the uplink portionof the TDD communication path. Without the uplink guard band 1114, thistemporal overlap can cause interference between communication schemesoperating in the first frequency band 1104 and the second frequency band1102.

Similarly, the second portion 1112 of the first frequency band 1104 isshown as adjacent to the second frequency band 1102 and separate fromthe third frequency band 1106 by a downlink guard band 1116. Thedownlink guard band 1116 may be desirable because the uplink portion1130 of the third frequency band 1106 temporally overlaps the secondportion 1112 of the first frequency band 1104 that is associated withthe downlink portion of the TDD communication path. Without the downlinkguard band 1116, this temporal overlap can cause interference betweencommunication schemes operating in the first frequency band 1104 and inthe third frequency band 1106.

FIG. 11B shows a diagram 1140 that illustrates a first frequency band1144 associated with a TDD communication path. The diagram 1140 alsoillustrates a second frequency band 1142 associated with atemporally-asymmetric TDD communication path and a third frequency band1146 associated with a different temporally-asymmetric TDD communicationpath. In this example, the temporally-asymmetric TDD communication pathassociated with the second frequency band 1142 has an uplink time slotduration (e.g., between t₁ and t₄) that is longer than a downlink timeslot duration (e.g., between t₀ and t₁). The temporally-asymmetric TDDcommunication path associated with the third frequency band 1146 has anuplink time slot duration (e.g., between t₃ and t₄) that is shorter thana downlink time slot duration (e.g., between t₀ and t₃).

The first frequency band 1144, the second frequency band 1142, and thethird frequency band 1146 are similar to the first frequency band 1104,the second frequency band 1102, and the third frequency band 1106described above with respect to FIG. 11A. The first frequency band 1144has a first portion 1150 associated with an uplink portion of the TDDcommunication path. The first frequency band 1144 has a second portion1152 associated with a downlink portion of the TDD communication path.The second frequency band 1142 has a first portion 1160 associated withan uplink portion of the temporally-asymmetric TDD communication path.The second frequency band 1142 has a second portion 1162 associated witha downlink portion of the temporally-asymmetric TDD communication path.The third frequency band 1146 has a first portion 1170 associated withan uplink portion of the temporally-asymmetric TDD communication path.The third frequency band 1146 has a second portion 1172 associated witha downlink portion of the temporally-asymmetric TDD communication path.

The first portion 1150 of the first frequency band 1144 is shown asbeing adjacent to the second frequency band 1142 and separate from thethird frequency band 1146 by an uplink guard band 1156. The uplink guardband 1156 may be desirable because the downlink portion 1172 of thethird frequency band 1146 overlaps in time with the first portion 1150of the first frequency band 1144 that is associated with the uplinkportion of the TDD communication path. The second portion 1152 of thefirst frequency band 1144 is shown as being separated from to the secondfrequency band 1142 by a downlink guard band 1154 and adjacent to thethird frequency band 1146. The downlink guard band 1154 may be desirablebecause the uplink portion 1160 of the second frequency band 1142overlaps in time with the second portion 1152 of the first frequencyband 1144 that is associated with the downlink portion of the TDDcommunication path.

FIGS. 12A-12B are each a diagram depicting time and frequency aspects ofa TDD scheme with adjacent FDD and broadcast schemes, according toembodiments. FIG. 12A shows a diagram 1200 that illustrates a firstfrequency band 1204 associated with a TDD communication path. The TDDcommunication path can be symmetric or asymmetric. The diagram 1200 alsoillustrates a second frequency band 1202 associated with a wirelessbroadcast. The diagram 1200 further illustrates a third frequency band1206 associated with a downlink portion of an FDD communication path.

The first frequency band 1204 includes a first portion 1210 and a secondportion 1212. A spectrum bandwidth associated with the first portion1210 of the first frequency band 1204 is different from a spectrumbandwidth associated with the second portion 1212 of the first frequencyband 1204. The first portion 1210 of the first frequency band 1204 isassociated with an uplink portion of the TDD communication path. Thesecond portion 1212 of the first frequency band 1204 is associated witha downlink portion of the TDD communication path.

FIG. 12A shows the first portion 1210 of the first frequency band 1204as separate from the second frequency band 1202 by an uplink guard band1214 and separate from the third frequency band 1206 by an uplink guardband 1216. The uplink guard band 1214 may be desirable because thewireless broadcast associated with the second frequency band 1202 couldinterfere with the first portion 1210 of the first frequency band 1204associated with the uplink portion of the TDD communication path.Similarly, the uplink guard band 1216 may be desirable because thedownlink portion of the FDD communication path associated with thesecond frequency band 1202 could interfere with the first portion 1210of the first frequency band 1204 associated with the uplink portion ofthe TDD communication path. The second portion 1212 of the firstfrequency band 1204 is shown as being adjacent to both the secondfrequency band 1204 and adjacent to the third frequency band 1206.

FIG. 12B shows a diagram 1220 that illustrates a first frequency band1224 associated with a TDD communication path. The diagram 1220 alsoillustrates a second frequency band 1222 associated with a wirelessbroadcast and a third frequency band 1226 associated with an uplinkportion of an FDD communication path.

The first frequency band 1224, the second frequency band 1222, and thethird frequency band 1226 are similar to the first frequency band 1204,the second frequency band 1202, and the third frequency band 1206described above with respect to FIG. 12A. The first frequency band 1224has a first portion 1230 associated with an uplink portion of the TDDcommunication path. The first frequency band 1224 has a second portion1232 associated with a downlink portion of the TDD communication path.

The first portion 1230 of the first frequency band 1224 is shown asbeing separated from the second frequency band 1222 by an uplink guardband 1234 and adjacent to the third frequency band 1226. The uplinkguard band 1234 may be desirable because the wireless broadcastassociated with the second frequency band could would interfere with thefirst portion 1230 of the first frequency band 1224 associated with theuplink portion of the TDD communication path. The second portion 1232 ofthe first frequency band 1224 is shown as being adjacent to the secondfrequency band 1222 and separate from the third frequency band 1226 by adownlink guard band 1236. The downlink guard band 1236 may be desirablebecause the uplink portion of the FDD communication path associated withthe third frequency band 1226 could interfere with the second portion1232 of the first frequency band 1224 that is associated with thedownlink portion of the TDD communication path.

FIG. 13 is a flow chart illustrating a method for using an asymmetricTDD scheme, according to an embodiment. At 1310, after 1300, receivingsignals via a portion of a first frequency band over an asymmetric TDDcommunication path associated with the first frequency band. The firstfrequency band and the associated asymmetric TDD communication path canbe based on one or more embodiments described herein with respect toFIGS. 3-12B. At 1320, transmitting signals via a different portion ofthe first frequency band over the asymmetric TDD communication pathassociated with the first frequency band. After 1320, the processproceeds to 1330.

FIG. 14 is a flow chart illustrating a method for using an asymmetricTDD scheme, according to another embodiment. At 1410, after 1400, anasymmetric TDD communication path is operated over a first frequencyband. The first frequency band and the associated asymmetric TDDcommunication path can be based on one or more embodiments describedherein with respect to FIGS. 3-12B. At 1420, communicating signals viathe first frequency band over the asymmetric TDD communication pathassociated with the first frequency band. After 1420, the processproceeds to 1430.

FIG. 15 is a flow chart illustrating a method for using an asymmetricTDD scheme, according to yet another embodiment. At 1510, after 1500,operating a first communication portion of an asymmetric TDDcommunication path via an uplink portion of a first frequency band. Thefirst frequency band and the associated asymmetric TDD communicationpath can be based on one or more embodiments described herein withrespect to FIGS. 3-12B. At 1520, operating a second communicationportion of the asymmetric TDD communication path via a downlink portionof the first frequency band. After 1520, the process proceeds to 1530.

In one or more embodiments, the communication methods associated withasymmetric TDD communication paths described above with respect to FIGS.3-12B can be implemented in flexible-use spectrum. In one or moreembodiments, the communication methods associated with asymmetric TDDcommunication paths described above with respect to FIGS. 3-12B can beimplemented in spectrum having a dedicated use.

CONCLUSION

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not limitation. For example, the methods described herein caninclude various combinations and/or sub-combinations of the componentsand/or features of the different embodiments described. Althoughdescribed with reference to use with flexible-use spectrum forsatellite, terrestrial, and/or hybrid wireless communication systems, itshould be understood that the asymmetric TDD methods described hereincan be used with frequency bands dedicated for particular use and foruse with certain wireless communication systems. Moreover, theasymmetric TDD methods described herein can be used with frequency bandsin wired communication systems.

The invention claimed is:
 1. A method, comprising: sending a firstsignal over an asymmetric time division duplex (TDD) communication pathvia a first portion of a first frequency band, the first frequency bandbeing adjacent to a second frequency band and a third frequency band,the first frequency band being different from the second frequency bandand the third frequency band, the second frequency band including asynchronous TDD communication path, the third frequency band including afrequency division duplex (FDD) communication path; and receiving asecond signal over the asymmetric TDD communication path via a secondportion of the first frequency band different from the first portion ofthe first frequency band; wherein the first portion of the firstfrequency band and the second portion of the first frequency band havethe same time duration.
 2. The method of claim 1, wherein the FDDcommunication path in the third frequency band is an FDD uplink path. 3.The method of claim 1, wherein the FDD communication path in the thirdfrequency band is an FDD downlink path adjacent to the first portion ofthe first frequency band.
 4. The method of claim 1, wherein the secondportion of the first frequency band is adjacent to the second frequencyband and the second portion of the first frequency band is separatedfrom the third frequency band by a predetermined guard band.
 5. Amethod, comprising: sending a first signal over an asymmetric timedivision duplex (TDD) communication path via a first portion of a firstfrequency band, the first frequency band being adjacent to a secondfrequency band and a third frequency band, the first frequency bandbeing different from the second frequency band and the third frequencyband, the second frequency band including a synchronous TDDcommunication path, the third frequency band including a frequencydivision duplex (FDD) communication path; and receiving a second signalover the asymmetric TDD communication path via a second portion of thefirst frequency band different from the first portion of the firstfrequency band; wherein the first portion of the first frequency banduses a larger frequency range than the second portion of the firstfrequency band.
 6. A method, comprising: sending a first signal over anasymmetric time division duplex (TDD) communication path via a firstportion of a first frequency band, the first frequency band beingadjacent to a second frequency band and a third frequency band, thefirst frequency band being different from the second frequency band andthe third frequency band, the second frequency band including asynchronous TDD communication path, the third frequency band including afrequency division duplex (FDD) communication path; and receiving asecond signal over the asymmetric TDD communication path via a secondportion of the first frequency band different from the first portion ofthe first frequency band; wherein the first portion of the firstfrequency band uses a smaller frequency range than the second portion ofthe first frequency band.
 7. A method, comprising: sending a firstsignal during a first time interval and over an asymmetric time division(TDD) communication path via a first portion of a first frequency band,the first frequency band being disposed between, immediately adjacent toand mutually exclusive of each of a second frequency band and a thirdfrequency band, the second frequency band being mutually exclusive ofthe third frequency band; and receiving a second signal during a secondtime interval and over the asymmetric TDD communication path.
 8. Themethod of claim 7, wherein the first time interval and the second timeinterval are mutually exclusive time intervals; the first time intervalarising later in time than the second time interval.
 9. The method ofclaim 7, wherein a duration of the first time interval equals a durationof the second time interval.
 10. The method of claim 7, wherein thefirst portion of the first frequency band utilizes a smaller frequencyrange than the second portion of the first frequency band.
 11. Themethod of claim 7, wherein the second portion of the first frequencyband utilizes a smaller frequency range than the first portion of thefirst frequency band.
 12. The method of claim 7, wherein the secondfrequency band includes a synchronous TDD communication path and thesecond frequency band comprises a first portion synchronous with thefirst portion of the first frequency band and a second portion.
 13. Themethod of claim 12, comprising: sending a third signal over thesynchronous TDD communication path via the first portion of the secondfrequency band.
 14. The method of claim 13, wherein the sending of thethird signal via the first portion of the second frequency band occursduring the first time interval.
 15. The method of claim 12, comprising:receiving a fourth signal over the synchronous TDD communication pathvia the second portion of the second frequency band.
 16. The methodclaim 15, wherein the receiving of the fourth signal via the secondportion of the third frequency band occurs during the second timeinterval.
 17. The method of claim 7, wherein the third frequency bandincludes a frequency division duplex (FDD) communication path.
 18. Themethod of claim 17, comprising: sending a fifth signal over the FDDcommunication path via the third frequency band; the fifth signal beingsent over the FDD communication path during a third time intervalencompassing both the first time interval and the second time interval;the FDD communication path being separated by a downlink guard band fromthe asymmetric TDD communication path during the second time interval.19. The method of claim 17, comprising: receiving a sixth signal overthe FDD communication path via the third frequency band; the sixthsignal being received over the FDD communication path during a thirdtime interval encompassing both the first time interval and the secondtime interval; the FDD communication path being separated by a uplinkguard band from the asymmetric TDD communication path during the firsttime interval.
 20. The method of claim 17, wherein the first frequencyband arises in an advanced wireless spectrum range of 2155 to 2175 MHz.